Please remember to say, "Thank you," and "You're welcome", when….to the host

Has anyone seen Chris recently? I....................... to contact him since last Monday.

Mrs. Davis, ...... we saw at the lecture last week, is in London for a conference.

Anna and Lucy hurt...... when they fell down the college front stairs.

In which of the following sentences is all PUNCTUATION correct?

I really like Mrs. Taylor because she is a teacher.......... cares about her students.